I. Field of the Invention
The present invention relates to the treatment of congestive heart failure. More specifically, it relates to the guide catheter used to properly position a cardiac lead in the heart so that when the lead is electrically coupled to a cardiac rhythm management device, electrical pulses are delivered from the cardiac rhythm management device to the proper location of the heart.
II. Discussion of the Prior Art
Congestive heart failure (CHF) is a progressive weakening of the heart and loss of its ability to efficiently pump blood to the rest of the body. As CHF progresses, the heart becomes enlarged. Eventually, the sequence and timing of electrical pulses that makes a normal heart pump blood efficiently are lost. The ventricles of the heart beat in an irregular and uncoordinated manner so that inadequate blood flow results. CHF causes shortness of breath, fatigue, weakness, and swelling of the legs and abdomen.
CHF is a prevalent disease which is an increasingly important cause of cardiovascular morbidity and mortality. In 1994 there were over 840,000 hospital admissions for CHF. The prognosis of CHF was so poor that the one year survival of severely ill patients was only about 50%.
CHF has a variety of causes and is exacerbated by a variety of conditions. Increased cardiac output caused by anemia, hyperthyroidism, infection or pregnancy can contribute significantly to CHF decompensation. Cardiac events such as arrhythmia, myocardial ischemia or a pulmonary embolism can also lead to heart failure or the exacerbation thereof. Some drugs can also trigger CHF. These include anti-inflammatory drugs, steroids and antibiotics as well as anti-arrhythmic drugs, calcium channel blockers and tricyclic antidepressants. Diet, alcohol consumption, and the patient""s failure to observe prescribed fluid restrictions and medication regimens can also trigger CHF.
A variety of treatments have been used to treat CHF. CHF has typically been treated with drugs and changes to the patient""s lifestyle. Drugs used in the treatment of CHF include digoxin, diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, hydralazine and isosorbide dinitrate, beta blockers, and inotropic agents. Lifestyle changes typically relate to restriction of salt in the diet, limiting or eliminating alcohol consumption, and regular exercise.
In acute cases of CHF, surgical strategies have been used. Transplantation of the heart, implementation of ventricular assist devices, cardiomyoplasty, and ventricular remodeling are examples of surgical treatments used to treat CHF.
In many cases, the drug, lifestyle and surgical options listed above have proven to be less than satisfactory. Recently, a new form of treatment has been investigated by the assignee of this invention. This treatment is referred to as bi-ventricular pacing. It involves the use of a heart pacemaker and three leads. One lead is used to deliver electrical signals to the right ventricle. Another lead delivers electrical pulses to the left ventricle. The third is placed in the right atrium. Delivery of pulses to the respective ventricles is sequenced and timed to restore the normal electrical sequence to the heart, thus making the heart pump blood normally and in a more coordinated manner.
Placement of the leads on the exterior of the heart involves highly traumatic surgical procedures. Thus, techniques have been developed for inserting the leads into the appropriate position through the vasculature of the heart. Placing pacing leads into the right side of the heart in this manner, given the current state of the art, is a relatively easy task. However, passing leads through the vasculature of the heart and into proximity with the left ventricle can be quite difficult. Typically, the lead to be coupled to the left ventricle must be advanced through the coronary sinus and great vein of the heart into a descending vein that runs down along the left ventricle to the apex of the heart. The lead must enter the coronary sinus through the ostium located in the right atrium. Locating the ostium in the right atrium can be a difficult and time-consuming task. Reports suggest that even highly skilled surgeons have taken up to three hours locating the ostium using conventional guidewires and guiding catheters.
Heretofore, surgeons have typically used the tip of a guidewire to probe the atrium wall to find the ostium. Once the ostium is found, surgeons have had difficulty advancing the guide catheter into the ostium. Thus, there is a real need for an improved apparatus which can be used to assist the surgeon in locating the ostium and inserting the guide catheter and guidewire through the ostium and into the coronary sinus and great vein of the heart.
The present invention provides an improved tip for a guide catheter. This improved tip assists the surgeon in locating the ostium of the coronary sinus and advancing the guide catheter through the ostium.
The guide catheter of the present invention, like most guide catheters, includes a flexible wall that surrounds a lumen. The distal tip end of the wall has an opening. The lumen and the opening cooperate so that a guidewire, a cardiac lead or both can be inserted through the lumen and past the distal end of the guide catheter.
In one embodiment, the improved guide catheter of the present invention provides a plurality of fingers that extend distally from the distal end of the wall and surround the opening. The fingers are preferably made of a soft, pliable material. When the fingers contact the wall of the atrium they spread out away from the opening increasing the effective area of the tip of the guide catheter. This larger area, enhances tactile feel, making it easier and less time-consuming to locate the ostium. The fingers are all sufficiently soft and flexible that they fold back against the outside of the guide catheter wall as the tip of the guide catheter is seated in the coronary sinus.
In a second embodiment, the distal end is provided with a plurality of flexible tines that project outwardly from the tubular body of the guide catheter at the distal end of the guide catheter to increase the area of the guide catheter over that of the tubular body. The increased surface area decreased the time required to locate the ostium. Also, the tines can be used to anchor the distal tip of the guide catheter to the edge of the ostium so that the physician can advance a guidewire through the ostium and into the coronary sinus. The physician can then advance the guide catheter over the guidewire and into the coronary sinus.
In a third embodiment, a spring is attached to the distal end of the catheter body. When the spring comes into contact with the atrial wall, it deflects outwardly expanding the surface area of the catheter tip. Again, the expanded area of the catheter tip serves to reduce the time necessary to locate the ostium. When the ostium is located, the spring anchors the guide catheter to the ostium so that the guidewire can easily be advanced into the coronary sinus. The guide catheter can then be advanced into the coronary sinus by sliding it over the guidewire. In a fourth embodiment, both the tines and spring described above are provided.
A better understanding of the present invention will be gained from a review of the following detailed written description of the invention with reference to the accompanying drawings. This description is not intended to be limiting, but is provided to comply with the disclosure requirements of the patent statutes.